Note that when none of the channels on the Model 7158 card are energized, terminals 2 and 4 are connected to the LO of the picoammeter (pA), which electrically is the guardterminal.
By definition, the guardterminal is nearly at the same potential as the high impedance terminal, so the guardterminal will be at the same potential as the magnitude of the voltage source.
根据定义,保护端与该高阻端处在几乎相同的电位,所以保护端就与电压源为相同电位。
3
The sizes of epidermis cell, the lengths of stomatal guard cells and of the terminal cells of T-hair are only quantitative characters, but not of much significances in systematics.